Among existing various radiation detectors, solid scintillator detector solid scintillator detectors are widely used and have great demand, and possess characteristics such as a compact volume and a high detection efficiency. In the solid scintillator detector, a detector assembly composed of a scintillator (cesium iodide, cadmium tungstate, etc.) and a photosensor (photodiode, photomultiplier tube, etc.) is a core component and also the most important part for affecting the detector performance index. In general, detection principle of the scintillator detector is that the scintillator absorbs the incident ray energy and converts the energy into scintillation light in equal proportion (the spectral range is generally between a near-infrared to a near-ultraviolet). Flashing light is absorbed by the photosensor and converted into electrical signals, and the electrical signals are transmitted to a readout circuit of the detector for further treatment.
The typical detector assembly is formed by coupling the scintillator to the photosensor through an optical adhesive. The coupling portion is between the light-exiting surface of the scintillator and the light-sensing surface of the photosensor. The optical adhesive has a higher optical refractive index and can reduce variation of the reflective index on an optical path from the scintillator to the photosensor, and thus improve the transmission efficiency of scintillation light. In addition, optical adhesive also has a certain bonding strength and hardness, the scintillator and the photosensor can be secured such that the relative location therebetween cannot be changed.
In a majority of operation environment of the detectors such as at a temperature of −25° C. to 40° C., and at a humidity of 0% to 60%, the detector assembly has a stable performance. But in a high-temperature and high-humidity environment such as at a temperature of over 70° C., and at a humidity of over 80%, it can be observed that sensitivity of the detector assembly (the most important performance index) will gradually decrease as the time increases, water molecules in the air have high density, the optical adhesive penetrated between the of the scintillator and the photosensor reaches a bonding surface to reduce bonding strength between the adhesive and the device, and thereby separating the adhesive from the device. The optical path with larger refractive index is formed between the separated adhesive and the device such that transmission efficiency of the flashing light can be reduced.
The above information disclosed in the Background is merely used to reinforce understanding of the background knowledge of the present disclosure, and thereby may contain information that is already known by a person of ordinary skill in the art.